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(No Model.)

R. M. LOCKWOOD 8v S. H. BARTLETT.

Transmitter for Telephones.

No. 229,152. Patented June '22, 1880;

Inventor:

Witnesses .1

04 K/MW;

. N.FEIERS. PNOm LlTiGOGRhPl-IER, WASHINGTON. D C.

UNITED STATES PATENT OFFICE.

ROBERT LOOKWOOD AND SAMUEL H. BARTLETT, OF NEW'YORK, N. Y., ASSIGNORS OF ONE-HALF OF THEIR RIGHT TO CHARLES F. LIVERMOBE,

OF SAME PLACE.

TRANSMITTER FOR TELEPHONES.

SPECIFICATION forming part of Letters Patent No. 229,152, dated June 22, 1880.

Application filed March 9, 1880.

To all whom it may concern:

Be it known that we, ROBERT M. LooK- woon and SAMUEL H. BARTLETT, of the city, county, and State of New York, have invented certain new and usefullmprovements in Transmitters for Telephones or Vocal Telegraphs, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which Figure 1 represents a vertical section through our improved receiver; and Fig. 2 represents, in perspective, a portion of the non-resonant block, hereinafter described, showing an ar- I 5 rangement of metallic points and a form of block for giving increased surface exposure to the sound-waves.

Similar letters of reference denote corresponding parts in both figures.

The transmitter is substantially the same in its arrangement of parts as that described in another application of even date herewith, and needs therefore to be described only so far as is necessary to an understanding of the present improvement, which consists in perforating the non-resonant block constituting the body of the transmitter, and upon the surface of which the sound-waves impinge, and thereby increasing the surface exposed to the sound-waves; and, further, in providing the walls of such openings or perforations with a series of radially-arranged metallic spokes or points, which enter the non-resonant body of the transmitter, and thereby tend to concentrate the sound-waves therein, as hereinafter explained.

in the accompanying drawings, A represents the base-plate, to which the non-resonant block B and the screw or binding-posts G G are secured. b b are the bars or strips of carbon or other conducting material embedded in the block B, and b the connecting button. a c are the insulating-strips interposed between the carbon strips and the ends 4 5 or arms 61 d of the magnet D, said arms penetrating the base-plate A and block B, and resting in contact with the non-conducting strips 0. F F are helices secured in separate sockets in the block B, surrounding the ends of the arms d d. h and h are the wires connecting the binding-posts with the carbon (No model.)

plates and helices, said parts being arranged and operating in substantially the same manner as is described in another application, above referred to. p

For the purpose of giving increased exposed surface to thenon-resonant block B without correspondingly increasing its bulk we form one or more perforations, B through it, so placed as not to expose or uncover the carbon bars or conductors embedded in it, thereby adding the walls of the perforations to the area of surface exposed to the sound-waves, and into the wall of this perforation, which is best made cylindrical in form, are inserted one or more circles of fine metallic rods or points having, by preference, the radial arrangement, and placed near the ends of the perforations, as shown in the drawings. These points take up the sound-wave and convey it, by mechanical vibration or otherwise, to the non-resonant block, whence it passes by what we term molecular disturbance to the carbon bars and button, and'thence, through the wires h 71 and through the binding-posts G G, to the main-line wires, for transmission in the manner explained in another application, referred to.

The construction described, as will readily be seen, adds greatly to the surface of the transmitter exposed to the sound-waves, and, whether by mechanical vibration of the points or otherwise, adds greatly to its efficiency.

It will be apparent that the form of the opening in the block B and the arrangement of the points, as well as the material of which the latter are formed, may be varied without departin g from the invention herein described.

Having now described our invention, we claim- 1. The non-resonant block or body of the transmitter, provided with one or more perforations, substantially as and for the purpose described.

2. The non-resonant block or body, having the'perforations or openings, provided with the points penetrating the walls of said openings, substantially as described.

ROBT. M. LOOKWOOD. SAMUEL H. BARTLETT. Witnesses:

F. L. OURAND, ALEX. MAHON. 

